The present invention relates to a door latch device provided in a door of a vehicle, and particularly to a vehicle door latch device in which a door is still closed even if an outer panel of the door is deformed by impact.
A vehicle door latch device comprises a base member fixed in a door; a latch supported on the base member to engage with a striker of a vehicle body; a ratchet which engages with the latch to prevent the latch from turning; an outside lever pivotally mounted to the base member about a pivot shaft extending longitudinally of the vehicle for transmitting motion of an outside handle via a motion-transmitting member when the door is opened; and various levers for turning the ratchet in a releasing direction for disengaging from the latch.
In the door latch device, the outside lever is connected to the outside handle on an outer panel of the door. Thus, the motion-transmitting member and a connecting portion connected to the lower end of the motion-transmitting member project from the side edge toward the outer panel outward of the vehicle,
The outer panel is deformed inward of the vehicle by impact, and the outer panel can come in contact with the connecting portion or motion-transmitting member through the deformation. The outside lever turns in a releasing direction for opening the door, and the door is likely to open accidentally. It is necessary to make a space between the outer panel and door latch device broader, but a room space of the vehicle becomes smaller.
In view of the disadvantage in the prior art, JP60-55671 B2 and U.S. Pat. No. 8,128,151B2 disclose a door latch device or a door lock device in which a door is still closed even if an outer panel is deformed by impact thereby preventing the door from opening accidentally.
The door lock device in JP60-55671B2 comprises a lift lever connected to an operating handle to lock and unlock the door; a resilient member supporting the lift lever to be inclinable; and a projection which comes in contact with the lift lever at inclination of the lift lever to prevent the lift lever from turning when the lift lever is inclined. By impact, an external force caused by door deformation acts to the lift lever, and the lift lever moves to a position where it contacts the projection via the resilient member thereby preventing the lift lever from turning in a lock-releasing direction to hold the door closed, but there is a problems as below.
The lift lever is elastically supported in the middle by a shaft and a compression spring around the shaft. A supporting force of the lift lever is likely to become weaker due to aging deterioration of the resilient member and sliding wear of the resilient member with the head of the shaft. By vibration, the lift lever is loose about the middle in a thickness direction during turning, and the extended end of the lift lever is likely to go away from the end of a pole actuated by turning the lift lever, which lacks reliability. Furthermore, when a turning force acts to the lift lever, it is not possible to prevent the lift lever from turning, which is disadvantageous.
In the door latch system in U.S. Pat. No. 8,128,151B, if the door latch system is moved inward of the vehicle through inward deformation of the outer panel of the door, the drive rod connected to the door handle and the latch-release unit of the door latch system comes in contact with the drive rod striking member mounted on the inner panel and is moved outward of the vehicle, thereby disengaging the drive rod from the latch release unit, so that the door is still closed. However, when the door latch system is moved inward of the vehicle due to inward deformation of the outer panel close to the door latch system, the drive unit is disengaged from the latch release unit effectively, which is advantageous. But it is difficult to set the drive rod striking member in position, which is unreliable as a door lock device.
It is necessary to provide the drive rod striking member, and there is a problem in layout in the door.